Reaming bit



1957 R. A. CUNNINGHAM EI'AL 2,802,643

REAMING BIT Filed May 29, 1955 37 Q I Robefl A. Cunninyhafi ErwinAMorlan Lyle L Payne I INVENTORS 0 BY I ATTORNEY States Patent Office2,802,643 Patented Aug. 13, 1957 2,802,643 REAMING BIT Robert A.Cunningham, Erwin A. Morlan, and Lyle L.

Payne, Houston, Tex., assignors to Hughes Tool Company, Houston, Tex, acorporation of Delaware Application May 29, 1953, Serial No. 358,272 2Claims. or. 255-330 This invention relates to reaming bits and hasparticular reference to a reaming bit which is run in a well bore to cutto gage an undersize hole which was drilled undersize by use of asmaller drill bit or by use of one which became undersize because ofwear or distortion of parts.

In thev drilling of deep earth bores drill bits are subject to wear onboth'the leading cutting elements and the gage cutting structure. Alsofrequently the drill bit is so damaged, while being lowered into a boreproduced by, preceding bits, that drilling .accomplished by such a bitproduces an undersize hole. If then'a new drill bit is lowered into thewell bore to drill deeper, such drill bit is required to first ream aportion of the hole before reaching bottom. This reaming operation oftenproduces such destructive effects upon the new bit that, when bottom isreached, it is necessary to withdraw and replace the bit with asucceeding new bit in order that a desired gage of hole is provided asdrilling ahead is again resumed.

It is the primary object of the invention to provide a reaming bit thatis capable of effectively reaming an undersize hole to bottom, so thatthe succeeding drill bit attached to the drill stem and used fordrilling ahead will be in unimpaired condition when it reaches bottomand will therefore produce a maximum of additional hole of full nominalgage.

Another object is to provide a reaming bit having roller reaming cuttersso mounted that the bit will efficiently cut to gage a large amount ofhole thereby conserving bits designed for drilling ahead.

Still another object is to provide a reaming bit in which the cuttersare so mounted that inward thrust of the cutters is effectivelyresisted.

Another and more specific object is to provide a reaming bit comprisinga head having downwardly and inwardly extending shafts thereon, reamingcutters on said shafts and a thrust body to rigidify the structure andto assume at least a portion of the inward thrust upon the cuttersduring reaming.

Cln one form the invention also comprehends the use of antifrictionhearings in the cutters so arranged as to assume both radial and axialloads and in this manner such bearings assume a portion of the inwardthrust of the reaming cutters thus assisting in holding the cutters togage.

It is also an object to provide a reaming bit having large, sturdycutters with adequate clearances thereby facilitating the removal ofcuttings from the vicinity of the bit.

Another object is to provide a structure in which flushing fluid may bejetted downwardly between cutters to facilitate disintegration of theearth formations and effectively remove the cuttings from the cuttingstructures.

These and other objects and advantages of the invention will be morefully apparent from the following description and the drawings in which:

Fig. 1 is a view, partly in section and partly in elevation, of areaming bit embodying the invention;

Fig. 2 is a bottom plan view of the disclosed embodiment of the reamingbit, and

Fig. 3 is a bottom plan view of a modified form of thrust bodycomprising an element of the reaming bit,

The embodiment of the invention shown in the drawings is a three-cutterreaming bit, Fig. 1 showing a sectional view through one half of thebit, the other half of the bit being shown in elevation and the rollingcutter there shown being rotated into the plane of the paper to moreclearly show the structure. The bit is shown at 1 and comprises a head 2having a threaded pin 3 at its upper end for attachment to the lower endof a drill string. The head has three downwardly extending legs 4 eachof which is provided with an inwardly extending shaft 5 terminating in areduced end '6 upon which the thrust body 7 is mounted. Cutters '8, 9and 10 are rotatably mounted on the shafts between the surfaces 11 and12 on the leg 4 and the thrust body 7 respectively.

T he head 2 is preferably made up of segments as shown at 14, 15 and 16,these segments being integrally united, as by welding as is well knownin the art, to complete assembly of-the bit. Each segment carries one ofthe legs 4 and the ass-ociatedshaft 5 upon which one of the cutters ismounted.

A's clearly shown in Fig. l the shaft 5 of the disclosed embodiment iscomposite in that the reduced end portion 6 is made up as a separatepart press fitted into a complemental bore in the end of the outermostportion of the shaft. Such end portion has a cylindrical portion 31intermediate its ends whereby there is provided an inwardly facingshoulder 36 to serve a purpose that will be further explained.

Since the shaft 5 extends both inwardly and downwardly the thrust body 7is generally pyramidal in shape. Openings 17 in the respective faces 12tightly receive the ends 6 of the shafts whereby the bit structure ismade adequately rigid and there is provided an outwardly facing thrustsurface at the inner end of each of the shafts.

The thrust body 7 is preferably multi-foliolate as best seen in Fig. 2.In a three-cutter structure, as shown, the body has three lobes asindicated at 20, 21 and 22. To further explain, the nether face of thebody is channeled upwardly and outwardly from the axis of rotationof'the bit, as shown at 23, intermediate vertical planes passing throughthe longitudinal axes of openings 17 in the thrust body. The channels 23interesct the outer faces of the body 7 upwardly from the nether face ofthe body and hence form the lobular or multifoliolate structure abovedescribed. There is thus provided a structure of adequate strength andrigidity and at the same time the channels 23 serve to conduct cuttingsand flushing fluid outwardly and upwardly so that the flushing fluid canremove the cuttings from the vicinity of the bit.-

The cutters 8, 9 and 10 are generally disk like, shown as frusturn-s ofcones, contoured internally complementary to the shaft 5 to formraceways to receive roller bearings 24 and ball bearings 25. The latterare insertible into their raceway, after the cutter and rollers havebeen assembled on the shaft, by way of the bore 26 in the bit leg 4- andthey are held in assembled relation by means of a plug 27 secured inplace as by means of welding as indicated at 28.

The cutters have an inwardly extending flange 30 at their innermost endsand this flange fits about the cylindrical portion 31 of the shaft. Italso provides an inwardly facing thrust surface in confronting relationwith the surface 12 on the thrust body 7. It seems apparcut that thisstructure serves to assume inward thrust of the cutters as the bit isrotated to effect reaming action. Such action is accomplished by thecutting action f the teeth 32 and the crushing or cutting action of thegage surfaces 33 to ream ahead and to maintain gage of the reamed hole.Since the ball bearings 25 are so arranged as to assume both radial andaxial components of load a portion of the inward thrust is also borne bythese hearings.

To enhance the wear resistant properties of the confronting thrust faceson the inner end of the cutter and the thrust body 7 these faces aregrooved and filled with wear resistant metal 34 and 35.

Obviously the inner end 6 of the shaft may be a separate piece pressfitted into a complemental bore in the inner end of the shaft as shownand already described, or the shaft may be an integral unit in themanner shown in U. S. Patent No. 1,983,316. In either event there isprovided an inwardly facing shoulder 36 in engagement with the thrustface 12 on the body '7. This assures a fixed space within which thecutter is mounted to rotate upon the shaft 5. It also assists inproviding a structure that is sufficiently rigid that it is capable ofresisting both static and shock loads imposed from normal use of thebit.

To more fully understand the structure and operation of the disclosedembodiment it will be assumed that the cutters 8, 9 and 10 are firstmounted upon their respective bit head segments of which two are shownat and 16, it being understood that as many segments will be used asthere are cutters on the bit.

The reduced end 6 of each shaft is then forced into its complementaryopening in the thrust body 7. The segments are then in assembledrelation and are integrally united, as by welding, to form the bit head2. The assembled bit is then attached to the lower end of a drill stringand is lowered to such level as reaming is to begin. Continued loweringand rotation of the bit progressively cuts away the ledge that is formedand at the same time the gage cutting structure or surfaces 33 maintaindesired gage. Inward thrust of the cutters is assumed by thecomplementary thrust surfaces 34 and 3S and by the ball-s 25.

When reaming, the bore previously drilled ahead is usually filled withwell fluids and detritus. To facilitate removal of such detritus,agitator or cutter blades 37 are provided on the nether face of thethrust body 7. Flushing fluid pumped downwardly through the passages 38in the bit head picks up the cuttings and detritus about the cutters andthe thrust body 7 and they move upwardly with the flushing fluid throughthe annulus in the well bore about the drill string to which the bit isattached. The channels 23 in the nether face of the thrust body 7facilitate the movement of flushing fluid and detritus from about thebit. 9

*In Fig. 3 the thrust body 7 is' shown provided with an axial bore 40which is bottomed where it transects 4 the openings 17. Hence the innerends 6 of the shafts 5 are exposed within this bore. With this featureof construction it is intended that weld metal shall be deposited withinthe opening 40 to form an integral bond between the metal of the thrustbody and the inner ends 6 of the shafts '5.

Broadly the invention comprehends a reaming bit that possessessufiicient strength and wear resistant characteristics that it iscapable of reaming to gage a large extent of undersize earth bore.

We claim:

1. In a reaming bit, a bit head, downwardly extending legs thereon,inwardly extending shafts on said legs, the inner end of each of saidshafts terminating in a cylindrical portion and a reduced end portionforming a shoulder therebetween, a thrust body mounted upon the reducedend portions of the shafts, said thrust body having outwardly facingthrust surfaces in engagement with said shoulders and extending radiallyoutwardly the-refrom, a rolling cutter on each of said shafts, each ofsaid cutters having a bearing surface rotatable upon said cylindricalportion of the shaft and a thrust surface complemental to and engageablewith the outwardly extending portion of the associated thrust surface onthe thrust body.

2. in a reaming bit, a bit head, downwardly extending legs thereon,inwardly extending shafts on said legs, the inner end of each of saidshafts terminating in a cylindrical portion and a reduced end portionforming a shoulder therebetween, a thrust body mounted upon the reducedend portions of the shafts, said thrust body having outwardly facingthrust surfaces in engagement with said shoulders and extending radiallyoutwardly therefrom, a rolling cutter on each of said shafts, anantifriction bearing between the cutter and shaft outwardly from saidcylindrical portion thereof, an inwardly extending flange on the innerend of said cutter rotatable about said cylindrical portion of the shaftand presenting a thrust surface complemental to and engageable with theassociated thrust surface on the thrust body.

References Cited in the file of this patent UNITED STATES PATENTS1,388,424 George Aug. 23, 1921 1,983,283 Garfield Dec. 4, 1934 1,983,316'Scott et al. Dec. 4, 1934 2,058,628 Reed Oct. 27, 1936 2,068,375Catland Jan. 19, 1937 2,086,682 Scott July 13, 1937 2,177,866 CatlandOct. 31, 1939 2,216,894 Stancliif Oct. 8, 1940 2,293,603 Francis Aug.18, 1942 2,329,751 Fermier Sept. 21, 1943

